■ 53 percent of respondents say the United States is less powerful than a decade ago;

■ 70 percent believe the United States is less respected;

■ 52 percent agreed that “the US should mind its own business internationally and let other countries get along the best they can on their own.”

For Bruce Stokes, director of Global Economic Attitudes at Pew, these findings describe “an unprecedented lack of support for American engagement with the rest of the world.”

On the surface, American public skepticism about our global role is understandable. Since the 9/11 attacks, the United States has fought two deeply unpopular land wars in Afghanistan and Iraq — the longest in our history. We suffered through the most damaging economic crisis since the Great Depression and watched as pressures rose on the poor and middle class. President Obama spoke for millions of Americans when he said in 2011 that it was “time to focus on nationbuilding here at home.”

But there are worrisome signs that support for US international leadership is breaking down in Congress. On the far left of the Democratic Party, there is visibly less support for sustaining world-class military and diplomatic capabilities. Meanwhile, the Tea Party sometimes gives the impression it wants to dig a giant moat around the country with drawbridges pulled up — permanently — to separate us from the rest of the world.

The problem with this line of thinking, of course, is that while isolation and retreat may have been perfectly rational responses to the world of 1814, they are recipes for foreign policy failure in the more highly integrated world of 2014. The Atlantic and Pacific oceans did not stop the 9/11 hijackers and won’t deter cyber criminals and terrorists waiting to strike in the future. The global economy knits together every nation on earth. That is why an increasing number of American jobs depend on our ability to export, trade, and invest competitively overseas.

In a very real way, the fate of every person on earth is now linked as never before. That is the tangible import of climate change, human trafficking, and the drug and crime cartels that plague every country in the world.

The United States serves, as Princeton’s John Ikenberry puts it, as the global “system operator.” By any metric of power — political, military, economic — the United States is still, by far, the most influential country in the world. China, India, and Brazil — the three great rising powers — are neither ready nor willing to replace us. And we should not want to live in a world dominated in the future by an autocratic and bullying Beijing.

In her gripping 2013 book, “Those Angry Days,” Lynne Olson chronicled the titanic public battle between the isolationist hero Charles A. Lindbergh and the interventionist President Franklin D. Roosevelt on the eve of the Second World War. It was not at all a given in 1939 to 1941 that FDR would finally defeat the isolationists who would have kept us criminally neutral in the battle against Hitler.

Fortunately, we face no isolationist movement in 2014 as dramatically powerful as Lindbergh and his allies in the US Senate before Pearl Harbor. The main lesson of that time, however, applies today. The United States needs to lead internationally, however burdensome that may sometimes be.

But, many of America’s closest friends are worried about us. In London last week, I listened to a litany of concerns about the consistency and durability of US global leadership. Could it be, some wondered, that in our understandable desire to withdraw from Iraq and Afghanistan, we may have pulled back too much from the rest of the Middle East, especially Syria and Egypt?

In a recent column that should be read carefully in Washington’s corridors of power, the influential British Financial Times columnist Philip Stephens warned starkly: “The US remains the only power that matters everywhere, but Washington no longer thinks that everywhere matters.”

Nicholas Burns is a professor of the practice of diplomacy and international politics at Harvard’s Kennedy School of Government. Follow him on Twitter @rnicholasburns.